worklog : build android from source

取得 source 後，可以到 build 下看看..

build/core/build-system.html

然後，run

build/envsetup.sh

就可以多出幾個command，可以用 "help" 指令 (run 完後直接key "help")看一下..

Invoke ". build/envsetup.sh" from your shell to add the following functions to your environment:
- croot:   Changes directory to the top of the tree.
- m:       Makes from the top of the tree.
- mm:      Builds all of the modules in the current directory.
- mmm:     Builds all of the modules in the supplied directories.
- cgrep:   Greps on all local C/C++ files.
- jgrep:   Greps on all local Java files.
- resgrep: Greps on all local res/*.xml files.
- godir:   Go to the directory containing a file.

Look at the source to view more functions. The complete list is:
add_lunch_combo cgrep check_product check_variant choosecombo chooseproduct
choosetype choosevariant croot findmakefile gdbclient get_abs_build_var
getbugreports get_build_var getprebuilt gettop godir help isviewserverstarted
jgrep lunch m mm mmm pid printconfig print_lunch_menu resgrep runhat runtest
runtest_py setpaths set_sequence_number set_stuff_for_environment settitle
smoketest startviewserver stopviewserver tapas tracedmdump

其中有關"mm" 這個command 的使用方法，在 SipX Android Build Environment 有提到。
這個 build-system.html 也包含很多其他的說明，像是 # 如何增加一個 project 到 android build system # 各種 build target 的差異 # 各種 clean 的差異